FIG. 1 illustrates a relay node (RN) 120 and user equipments (UEs) 131 and 132, which are present in the service area of an eNodeB (eNB) 110 in a wireless communication system 100. The relay node 120 can transmit data received from the eNB 110 to the UE 132 located in the area of the relay node and transmit data received from the UE 132 to the eNB 110. In addition, the relay node 120 can support extension of a high data rate area, improvement of communication quality at a cell edge and provision of communication to the inside of a building or an area out of the service area of the eNB. FIG. 1 shows a UE (referred to as a macro-UE or M-UE hereinafter) that directly receives a service from the eNB, such as the UE 131, and a UE (referred to as a relay UE or R-UE hereinafter) that receives a service via the relay node 120, such as the UE 132.
A wireless link between the eNB 110 and the relay node 120 is referred to as a backhaul link. A link from the eNB 110 to the relay node 120 is referred to as a backhaul downlink and a link from the relay node 120 to the eNB 110 is referred to as a backhaul uplink. A wireless link between the relay node 120 and the UE 132 is referred to as an access link. A link from the relay node 120 to the UE 132 is called an access downlink and a link from the UE 132 to the relay node 120 is called an access downlink.
When the relay node 120 controls the corresponding cell, the UE 132 can recognize the relay node 120 as a normal eNB. When another UE functions as the relay node 120 (a relay node of this type is called a UE-relay), the UE 132 cannot recognize the presence of the relay node 120.